Ask your Expert: Nico teWinkel - Software Engineer who specialises in firmware, C and Java.

Hello Arduino guys!

This is the first time ever, that i am entering an arduino forum and there are so many options around here, i am not even sure that i am posting my question in the right place - if i am not, can you please explain or send me links or keywords for the correct pages? Thanks a lot!

Here is my question:

I am trying to build a robot, that uses the "Bluecontrol" android application.

Here is the Bluecontrol app on google play:

https://play.google.com/store/apps/details?id=com.gundel.bluecontrol&feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5ndW5kZWwuYmx1ZWNvbnRyb2wiXQ..

The robot, called "MegaPed", building instructions and arduino sketch are detailed on www.instructables.com, on this page:

http://www.instructables.com/id/MegaPed/

I have done everything exactly according to written and drawn instructions on that page, with only one change:

I have switched this BlueSMiRF bluetooth module, which is quite expensive:

http://www.amazon.com/SparkFun-Bluetooth-Modem-BlueSMiRF-Silver/dp/B004GTUI76/ref=sr_1_5?s=electronics&ie=UTF8&qid=1332730295&sr=1-5

With this JY-MCU Arduino Bluetooth Wireless Serial Port Module:

http://www.ebay.com/itm/251258723414?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Now, my problem is, that after uploading the sketch - My android smartphone, is trying to connect with the bluetooth module, but shows that the module (called "linvor" on the smartphone screen) is: "Paired but not connected" - And i am unable to proceed and control the robot from the Bluecontrol application.

Maybe you can help me solve this problem or refer me to someone who might help me to solve this problem?

Thanks a lot,

Roi Neustadt.

Hi Roi,

Probably the best thing to do is to just post your question once, as a new topic (marked as a question), in the Arduino forum. Posting the same question in many different areas makes it more difficult for people to work together to help you figure it out. For all the posts you've already made, you might want to edit them to point to the one central question.

Your project sounds like quite the interesting one, but unfortunately I don't know enough about the subject to be able to help much, sorry. I do have the same type of BT module as you have, and what you're working on is something that's on my want-to-do list, so if I have some time in the next week I will have a look.

Cheers,

-Nico

Hello Nico!

Thanks for these initial forum go about instructions!

I will be waiting to hear from you how you have managed with building the bot, the JY-MCU version !!

Thanks,

Roi.

Hi Roi,

A good step in debugging is to break it down into pieces. In this case you are debugging the BT connection, so step one is to test just the BT communications.

I tried it last night, by simply hooking the BT module to pins 10 and 11 and using it as a new serial port to read from. Then everytime something is read from BT it shows on the Serial monitor.

I was able to use the app to connect and send single characters to my serial terminal display. To connect the app to the linvor BT module, all I had to do is press the menu button and choose "connect". I was doing this on a Samsung Galaxy S with Android 2.3.

This is the code I used on my Arduino Uno, which is just a slight modification of the built in sample SoftwareSerial->TwoPortReceive.

/*

  Software serial multiple serial test

Receives from the software serial port,

sends to the hardware serial port.

*/

#include <SoftwareSerial.h>

// software serial #1: RX (=TX of BT module) = digital pin 10, TX (=RX of BT module) = digital pin 11

SoftwareSerial BTport(10,11);

void setup()

{

// Open serial communications and wait for port to open:

  Serial.begin(9600);

  // Start the software serial port

  BTport.begin(9600);

  Serial.println("Data from Bluetooth:");

}

void loop()

{

  // By default, the last intialized port is listening.

  // when you want to listen on a port, explicitly select it:

  BTport.listen();

  // while there is data coming in, read it

  // and send to the hardware serial port:

  while (BTport.available() > 0) {

    char inByte = BTport.read();

    Serial.write(inByte);

  }

}

Hello Nico!

I have tried to compile, upload and watch trough the serial monitor the test code here, that you sent me and it was working fine.

Then i discovered that i need to connect to the bluetooth module, from within the Bluecontrol app and not from the smartphone bluetooth settings - and at last the bluetooth module led stopped blinking and turned on constantly - and the Bluecontrol app gave an indication that it is connected to the "Linvo".

I though that at last i will be able to make the robot servos move, according to touch commands on the Bluecontrol, on my smartphone screen - but no, it still did not work.

Could that be because i have connected this time only one servo and not all the 4 in the diagram?

The servo was moving occasionally, just very small movements, but that could also be only because of unconstant voltage from the LiPo battery.

I tried to chage all the values in the code, which are tenths of microseconds to thousands of microseconds, in oredr to find out if the servo movements are random or originate from my pressing on the smartphone screen - but the servo did not start moving for longer periods.

Do you have any idea, how should i try to tackle the problem this time?

Thanks,

Roi.

Hi Roi,

Try adding some Serial.println statements to the robot sketch to display debug information on the Serial monitor to show that the robot is actually receiving the commands.

And/or instead of moving servos, turn on an LED for a second or so when a command is received. You could have one LED per servo or per command, for example.

I still haven't checked out that robot you pointed out... I really should try that out

Cheers,

-Nico

ps, great to hear you got the BT connected to your Arduino too!

And I just had a look at the robot on Instructables - pretty cool!

But it takes 19 braces, which the author seems to have 3D printed. Where did you get your I-braces? Did you 3D print them or did you manage to figure out a different ingenious solution for that?

Cheers,

-Nico

Hey Nico!

Finally i am on the horse!

Altough, still at the beginning of the physical building of the robot shape itself and thus, have not yet delt with the issue of 3D priniting these parts - but at last, i am able to press an arrow on the BlueControl screen on my smartphone and in return, the sevo makes a nice movement.

In 'retrospective', what i did were the follwoing things:

1.The first problem i had, was that i did not understand how to connect to the bluetooth module - and that had nothing to do with the IDE code, it is just that for some reason that i don't understand, you have to pair with the blue tooth modue throrugh settings, but you connect to the module from within the BlueControl app menu.

2.Getting to the code as it is now, was kind'a messy and i don't remember all i did - So, maybe the MegaPed code could have also worked for me, but since i had problems at the beginng, to tell if pressing the arrows on BlueControl, generates constructed small servo movements or if these movements are just random (servos act weird sometimes) - i just made a search for other similar projects and found a project, where i was able to deffinatly recognize that these small movements originate in pressing the app arrows.

3.I don't know why i always got only these very small movements from the servo, but when i was able to determie that it was for sure me, that causes these small movements, i started meshing pieces of code that i found here and there in other projects, into the areas of that code, which i thought were good candidates for the purpose of expanding the small movements into longer ones.

So - that's where i am right now: I found a project that is not MegaPed which uses it's own andriod app - this code uses a method that i don't understand much, which works by using the command DigitalWrite(motor_name,HIGH/LOW) - which only makes the servo move a little bit. Into the code areas, that use this command, within a Serial.read() loop and respond to the ASCII commands (sent from BlueControl - i changed the letters of original app, because BlueControl has more options than this app - e.g. the letters on the side panels), i inserted in these areas a command called Servo servo_name.write(servo_position), that gave me longer movements for the servo.

Here is the other project page, which i used as a framework:

http://letsmakerobots.com/node/27249

And here is the code, as it looks right now, and will go through more changes and learning process, on my side:

#include <Servo.h>

char val; // variable to receive data from the serial port

Servo roi;

int motor_left[] = {3, 5};

int motor_right[] = {6, 9};

int ledPin =  13;    // LED connected to digital pin 13

void setup() {

  Serial.begin(9600);       // start serial communication at 9600bps

int i;

for(i = 0; i < 2; i++){

pinMode(motor_left[i], OUTPUT);

pinMode(motor_right[i], OUTPUT);

pinMode(ledPin, OUTPUT);

}

}

void loop() {

  if( Serial.available() )       // if data is available to read

  {

    val = Serial.read();         // read it and store it in 'val'

  }

  if( val == 'U' )              

  {

    drive_forward(); 

  }

   else if( val == 'D' )              

  {

    drive_backward();

  }

   else if( val == 'L' )              

  {

    turn_right(); 

  }

   else if( val == 'R' )             

  {

    turn_left(); 

  }

  else if( val == 'C' )             

  {

    motor_stop(); 

  }

}

void motor_stop(){

   roi.attach(6);

digitalWrite(motor_left[0], LOW);

digitalWrite(motor_left[1], LOW);

digitalWrite(motor_right[0], LOW);

digitalWrite(motor_right[1], LOW);

// roi.attach(6);

// roi.write(90);

// delay(1000);

// roi.write(0);

// delay(1000);

// roi.write(180);

//delay(1000);

}

void drive_forward(){

digitalWrite(motor_left[0], HIGH);

digitalWrite(motor_left[1], LOW);

digitalWrite(motor_right[0], HIGH);

digitalWrite(motor_right[1], LOW);

roi.attach(6);

roi.write(90);

delay(1000);

roi.write(0);

delay(1000);

roi.write(180);

//delay(1000);

}

void drive_backward(){

digitalWrite(motor_left[0], LOW);

digitalWrite(motor_left[1], HIGH);

digitalWrite(motor_right[0], LOW);

digitalWrite(motor_right[1], HIGH);

roi.attach(6);

roi.write(90);

delay(1000);

roi.write(0);

delay(1000);

roi.write(180);

//delay(1000);

}

void turn_left(){

digitalWrite(motor_left[0], LOW);

digitalWrite(motor_left[1], HIGH);

digitalWrite(motor_right[0], HIGH);

digitalWrite(motor_right[1], LOW);

roi.attach(6);

roi.write(90);

delay(1000);

roi.write(0);

delay(1000);

roi.write(180);

//delay(1000);

}

void turn_right(){

digitalWrite(motor_left[0], HIGH);

digitalWrite(motor_left[1], LOW);

digitalWrite(motor_right[0], LOW);

digitalWrite(motor_right[1], HIGH);

roi.attach(6);

roi.write(90);

delay(1000);

roi.write(0);

delay(1000);

roi.write(180);

//delay(1000);

}

Let me know what you think!

All the best!

Roi.

Hey Nico!

Finally i am on the horse!

Altough, still at the beginning of the physical building of the robot shape itself and thus, have not yet delt with the issue of 3D priniting these parts - but at last, i am able to press an arrow on the BlueControl screen on my smartphone and in return, the sevo makes a nice movement.

In 'retrospective', what i did were the follwoing things:

1.The first problem i had, was that i did not understand how to connect to the bluetooth module - and that had nothing to do with the IDE code, it is just that for some reason that i don't understand, you have to pair with the blue tooth modue throrugh settings, but you connect to the module from within the BlueControl app menu.

2.Getting to the code as it is now, was kind'a messy and i don't remember all i did - So, maybe the MegaPed code could have also worked for me, but since i had problems at the beginng, to tell if pressing the arrows on BlueControl, generates constructed small servo movements or if these movements are just random (servos act weird sometimes) - i just made a search for other similar projects and found a project, where i was able to deffinatly recognize that these small movements originate in pressing the app arrows.

3.I don't know why i always got only these very small movements from the servo, but when i was able to determie that it was for sure me, that causes these small movements, i started meshing pieces of code that i found here and there in other projects, into the areas of that code, which i thought were good candidates for the purpose of expanding the small movements into longer ones.

So - that's where i am right now: I found a project that is not MegaPed which uses it's own andriod app - this code uses a method that i don't understand much, which works by using the command DigitalWrite(motor_name,HIGH/LOW) - which only makes the servo move a little bit. Into the code areas, that use this command, within a Serial.read() loop and respond to the ASCII commands (sent from BlueControl - i changed the letters of original app, because BlueControl has more options than this app - e.g. the letters on the side panels), i inserted in these areas a command called Servo servo_name.write(servo_position), that gave me longer movements for the servo.

Here is the other project page, which i used as a framework:

http://letsmakerobots.com/node/27249

And here is the code, as it looks right now, and will go through more changes and learning process, on my side:

#include <Servo.h>

char val; // variable to receive data from the serial port

Servo roi;

int motor_left[] = {3, 5};

int motor_right[] = {6, 9};

int ledPin =  13;    // LED connected to digital pin 13

void setup() {

  Serial.begin(9600);       // start serial communication at 9600bps

int i;

for(i = 0; i < 2; i++){

pinMode(motor_left[i], OUTPUT);

pinMode(motor_right[i], OUTPUT);

pinMode(ledPin, OUTPUT);

}

}

void loop() {

  if( Serial.available() )       // if data is available to read

  {

    val = Serial.read();         // read it and store it in 'val'

  }

  if( val == 'U' )              

  {

    drive_forward(); 

  }

   else if( val == 'D' )              

  {

    drive_backward();

  }

   else if( val == 'L' )              

  {

    turn_right(); 

  }

   else if( val == 'R' )             

  {

    turn_left(); 

  }

  else if( val == 'C' )             

  {

    motor_stop(); 

  }

}

void motor_stop(){

   roi.attach(6);

digitalWrite(motor_left[0], LOW);

digitalWrite(motor_left[1], LOW);

digitalWrite(motor_right[0], LOW);

digitalWrite(motor_right[1], LOW);

// roi.attach(6);

// roi.write(90);

// delay(1000);

// roi.write(0);

// delay(1000);

// roi.write(180);

//delay(1000);

}

void drive_forward(){

digitalWrite(motor_left[0], HIGH);

digitalWrite(motor_left[1], LOW);

digitalWrite(motor_right[0], HIGH);

digitalWrite(motor_right[1], LOW);

roi.attach(6);

roi.write(90);

delay(1000);

roi.write(0);

delay(1000);

roi.write(180);

//delay(1000);

}

void drive_backward(){

digitalWrite(motor_left[0], LOW);

digitalWrite(motor_left[1], HIGH);

digitalWrite(motor_right[0], LOW);

digitalWrite(motor_right[1], HIGH);

roi.attach(6);

roi.write(90);

delay(1000);

roi.write(0);

delay(1000);

roi.write(180);

//delay(1000);

}

void turn_left(){

digitalWrite(motor_left[0], LOW);

digitalWrite(motor_left[1], HIGH);

digitalWrite(motor_right[0], HIGH);

digitalWrite(motor_right[1], LOW);

roi.attach(6);

roi.write(90);

delay(1000);

roi.write(0);

delay(1000);

roi.write(180);

//delay(1000);

}

void turn_right(){

digitalWrite(motor_left[0], HIGH);

digitalWrite(motor_left[1], LOW);

digitalWrite(motor_right[0], LOW);

digitalWrite(motor_right[1], HIGH);

roi.attach(6);

roi.write(90);

delay(1000);

roi.write(0);

delay(1000);

roi.write(180);

//delay(1000);

}

Let me know what you think!

All the best!

Roi.